Electric motors are widely used in our modern life: in industrial applications; in land vehicles, such as cars, trucks, and mobile machinery; in airplanes and other airborne vehicles; in military applications; in mechanical and electrical devices used in medical technology; and in home appliances.
As the demand for electric motors has increased over the years—and continues to do so—many types of motors have been developed to satisfy the wide variety of applications and needs of our technologically oriented society. In the field of electric motors, for example, we can find high- and low-speed rotary motors, torque motors, linear motors, nanomotion motors, and many more, each developed to meet a specific purpose or purposes.
Since the invention of the first motor concept about 180 years ago, the construction of electric motors has been based on the concept of an internal, rotating body called a rotor and an outer, stationary body called the stator, each of which was concentrically located in respect to the other. The electromagnetic interaction between these two elements produces S-shaped magnetic lines which are then induced to be straightened, and the resultant semi-tangential vector results in the production of rotational moment.
In consideration of the weight-to-power ratio of lightweight electric motors, it is understood that a small, lightweight motor makes a trade-off due to its size in that the motor velocity is generally of a very high speed if the motor is small. Consequently, a high-reduction gear box is needed to obtain the desired speed.
In many applications gearboxes need to be used to engage with electric motors, either to reduce the speed and/or to increase the moment, or to convert a rotary movement into a linear movement. In practice, a parallel gear train gearbox, a planetary gearbox, or harmonic drive reducer can be used to reduce or increase rotary motor speed and/or moment. Alternatively, a screw and nut, or rake and pinion, can be used to convert rotary movement into linear movement.
Gearboxes that are connected to electric motors suffer from a few disadvantages. Gearboxes are normally connected to electric motors in serial, which increases the total assembly length and/or diameter of the combined unit. The weight of gearboxes is generally high. Furthermore, the add-on gear assembly tends to be noisy, expensive, and of low efficiency.
Thus it would be desirable to provide an innovative planetary, push-pull electromagnetic motor (PPPEM) that overcomes the above-mentioned disadvantages and improves on the current concept.